1. Field
This disclosure is generally related to slot assignment and reservation in a wireless dynamic TDMA network. More specifically, this disclosure is related to a method and an apparatus to facilitate slot adaptation with reservations by measuring the quality of time slots and sharing the slot quality information with neighbors in a wireless dynamic TDMA network.
2. Related Art
In a wireless dynamic TDMA network, time slots are assigned to nodes in a changing sequence. Such networks are used in wireless multihop data networks and are distinct from wireless cellular TDMA networks. In situations where nodes cannot communicate or are otherwise unaware of each other but share the same channel, these random sequences will likely overlap between non-communicating groups and cause intermittent signal interference. Depending on topology, this interference may be more or less persistent. In such a network, however, if reservations are used, the interference might become persistent and repetitive. In the worst case, interfering nodes choose to reserve the same slot, and the performance of that slot becomes unacceptably low.
Previous works on time slot assignment and re-assignment looks primarily at signal-to-interference and noise ratios (SINR), power control, frequency channel, or modulation as the system parameters. For example, in order to re-assign a wireless device between time slots on the same channel when there is high co-channel interference, the wireless device scans frequencies to find one with a good signal-to-interference ratio (SIR), and requests the found time slot from the base station. Upon decoding the request, the base station acknowledges the request and confirms the link. The base station continues monitoring the signal quality on its side and making adjustments based on its local information.
Most of these works are unrelated to the specific problem domain we consider, which is a common-channel wireless ad hoc data network with random time slot assignments using persistent time slot reservations, particularly when those time slot reservations are not dedicated to a specific flow between fixed neighbors. Hence, there is a need for a method and an apparatus for efficient slot adaptation with reservations by measuring the quality of time slots and sharing the slot quality information with neighbors in a wireless dynamic TDMA network. Based on the shared state, nodes may choose preferred time slots to reserve and avoid transmitting data on other slots with high interference.